Method of producing ammonia and the like.



J. E. BUCHER.

METHOD OF PRODUCINGAMMONIA AND THE LIKE.

APPLICATION FILED JAN 8.1914.

1, 1 38, 1 91. a Patented May 4, 1915.

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UNITED STATES ATEN 1 JOHN E. BUCHEB, 0F COVENTRY, RHODE ISLAND, ASSIGNORTO NITROGEN PRODUOTS COMPANY, OF PROVIDENCE, RHODE ISLAND, A CORPORATIONOF RHODE ISLAND.

METHOD OF-PRODUCING AMMONIA AND THE LIKE.

Original application filed October 21, 1912, Serial No. 726,924. Dividedand this application filed 1914. Serial No. 810,973.

. pounds.

The Process in question is essentially synthetic in character in itspreferred form, and was suggested by my work on the synthesis of cyanidsand on my processes for purifying: and preparing metals, in whichnitrogen plays an important part. Letters Patent for these processeshave been granted, the same being numbered and dated 're- December "2..1913; No. 1,082,8-5; dated December 30, 1913; No. 1,086,019, datedFebruary 3, 19H: and N 0. 1,087,900, dated February 17, 1914-.

One of the equations representing the fumlmuc-ntal ideas of catalysisand reversible reactions upon which ,these four patents are based is thefollowing:

4 (ll "2Na+2C+N +iron=2NaGN |-iron.

The present application is a division of mv application entitled Processtor fixing atmospheric nitrogen, filed October 21, till), Serial Number126,924, now Patent :'i ljltlhlrli, dat'cd March 24,1914, which re atesto a pro'ccssfor converting carbonates and the like into cyamds, as perequat on:

a N.. 10, 40+N iNtom-imn.

The present divisional application relates this connection that when thesource of the' metal anticipating in the reaction is such a compoundthereof as,- for example, is sodium carbonate, this compound, as well asthe car- Specification of Letters Patent.

Patented May 4, 1915.

January 8,

bon solvent employed,behaves,in efi'ect,catalyt-ically. In the saidapplication, of which this is a division, is to be found a presentationof much of the art relating to cyanid production, and since this art isnow of record in the parent application, specific reference thereto,together with considerable of the matter set forth in the parentapplication relating, to said ai't, or serving: par-' ticularly to pointout the essential difi'erences between the known processes and that;

more especially referred to in the parent application have been omittedfor brevity.

The hercina l ter described process accordingly aims to economically fixatmospheric nitrogen in such a form, 0. {1. ammonia. that it may beutilized either with or without subsequent operations, according to thenature of the ultimate product sought.

In the acconu'ianying drawings, which form a part hereof and in. whichlike refer ence characters designate like parts throughout the severalviews, I have exemplified one spectively as follows INo. 1,079,974,dated form of apparatus in which my process may be eliectuated. It is tobe' understood, however, that this apparatus is but one of many adaptedto the purpose in question, and that i lions may be made therein withoutdepartmgfrom the spirit of my invention. In

general .I ma y state. tliei'etore, that my said invention is to beregarded as limited only by the scope of the appended claims. I

Description, of lI-/I/m!'rnfus.-Refcrripg to the drawing; Figurel is alongitudinal \crlical section of a mullle furnace with rotorts inposition therein. Fig.- 2 is an end elevation of said furnace; the blastlamp being omitted for convenience of illustration.

Fig. 3 is a fragmentary section of one of the pipes or retorts, thescctionbeing taken on line III-III of Fig. 1. section of a retortadapted for the use oi air in the. process. I

Brickwork or other suitable material may be employed in the constructionof the mufl e 1, and one or more iron pipes 52, servinn as retorts, mayextend directly there'- through. v I

(aps or unions 3, serve to connect the ends of the retorts to the plpes4-5; those Fig. 4 is a similar designated 4- being the pipes forsupplying nitrogen or air as the. case may be.

he; gases, notably carbon monoxid, evolved during the operation of theprocess are conveyed away via pipes 5.

' A blast lamp 6 or other suitable source of heat may be disposed in thepreferably open end of the mufile and this apparatus should, of course,be capable of heating the retorts up to. the reaction temperatureemployed; which will be hereinafter very fully dis- If the process is tobe conducted in such fashionas to :permit the use of air, ratherthanfree nitrogen (which latter is, however,

= preferred where the process is so conducted us to yield ammoniadirectly in the manner hereinafter described), the .air is led inthrough pipes 4 and preferably first encounters one or more masses? ofcharcoal :or other suitable oxygen consuming material. These massespreferably substantially fill the pipes at the points where they aredisposed .so that all of the air is obliged to pass therethrough. Iprefer in such case to inter-pose wire gauze spacing or supportingscreens '8, or] the .like, between the charcoal and. the body of thereaction mixture 9 which is next encountered by the gases flowingthrough the pipe or retort; since it is desirable to keep the charcoalaway from the charge. If nitrogen .be' supplied as such,

. rather than mixed with oxygen in the form inexpensive source,'of themetalforming the base of the cyanogen compound to be incidentlyformeddurin'gr the operation.

Theory of operation. ,In chemical work,

it"is often necessaryto dissolve solids to make them reactive; and wealso know that when substances a re dissolved they very .fr'equntlybecome dissociated. These and many-similar.considerations point tov theconclusion that if the very complex and ordinarily comparatively inertcarbon can thus be dissolved it will not only acquire mobility butperhaps may also become less complex; thus'approaching the nascentcondition.

' Ironis one of the best solvents known for carbon. Hence a solidsolution. such as is obtained in the cementation process ofmanufacturing stcel, \\71ll form very quickly at the surface of tliemeta l; provided that it is not already there, as in carburizediron. Theconditions at this surface should be exceedingly favorable for chemicalreactions and the above mentioned results obtained by the use of finelydivided iron are in accordance with this view. Presumably a part atleastof the opera tion takes place as follows: the small quantity of sodiumvapor, formed according to equation 3, and thenitrogen come in contactwith the reactive surface of the carburized' iron where they combinevery quickly with the carbon dissolved in the surface of the iron,forming sodium cyanid. The vapor pressure of the gaseous sodium, is thusreduced and consequently another portion of sodium carbonate decomposesto reestablish the equilibrium. -This new portion of sodium vapor in tun combines with nitrogen and carbon at the surface of the iron, whichhas meanwhile become recarburized by taking up carbon from thecarbonaceous masses in contact therewith, or from the carbon in solutionin the mass of iron. The iron hence acts as a catalyzer'by undergoing aseries of decarburizations and recarburiza tions; resulting in theeflicient and continuous production-of reactive carbon for the process.The very quick combination of sodium at this catalytic surface reducesthe concentration of the sodium vapor steadily; and this materially aidsin producing a continuous liberation of sodium with the consequentcontinuous formation of'sodium cyanid. This'very simple theory, enablesus to deal intelligently with the many conditions which influence theprocess. Evidently the first requisite is to produce as efficient acatalytic or solution surface as practicable and to maintain itsefficiency during the process;

' Even when the conditions of surface and 'contactappear to be corrector nearly so, at times a lapse of 10 or 15 minutes may occur before anyvigorous reaction takes place. This may be due, insome cases, especiallywhen working at a relativelylow temperature, to the time consumed incarburizing the reactive surfaces of the catalytic material; andprobably also to changes in the relative disposition of fiuid and solidconstituents of the reactive mass by, for example, capillary action. Thetheory of the operation must therefore be borne in mind while the actualprocedure really a compromise between various factors. At onetemperature one factor becomes dominant; at another temperaturesometimes quite close to the first, another factor gains the ascendency,and so on. v y

Should my theory be faulty, which however I do not think is the case, itat any rate supplies a working hypothesis which vii-- ables us toachieve consistent and successful results.

Sources and condition, 0' catch 201', etc. A fine state of division 0the iron exposes a large surface and hence acts favorably. Similarly aline state of division of the carbon favors the quick carburization of.the iron by providing thorough contact at, what Imay term, the solutionsurfaces, or as l refer to term it in the aggregate-surface.

The catalytic agent, 2. g. iron, if used in solid form should be quitefinely powdered or in such other form as to expose, or to renderpossible the exposure of, a relatively enormous solution surface.Particularly is I this the case when the operation is conducted attemperatures materially below the eutectic point ofthe carbon-containingmaterial. If the iron be a coarse powder, insufficient surface willusually be provided, under such, conditions, to permit of the processbeingconducted efficiently. If, on

the other hand, it is too. finely divided, there is some tendency topack too tightly and thereby prevent diffusion of th gases and vaporsinvolved. On the who e, however, I prefer to divide the iron as finelyas possible and to provide forl diifusion in some suitable manner suchas will be hereinafter indicated.

When theparticles of catalytic material are relatively large, thesurface is correspondingly-small and the area of contact is likely to betoo small for quick and efiicient renewal of the. carbon content inthelcatalytic surface. Uuder the indicated conditions which I have foundconvenient in effectuating my process, when nitrogen and relatively fineand the graphite comparatively coarse, than when the relative sizes werereversed, i. e. when the iron was coarse and the graphite was fine. Thusiron Ph. G. IV. which is far finer than 100 mesh,

gafve very good results when: used with graphite which had been passedthrough a one 'hundred mesh sieve but which on the whole 3. as notnearly so finely divided as the iron. An even b tter result was obtainedwhen said'fine iron was used with graphite tinct maximum for thegraphite of inter-' of 60 to mesh. When, however, the

aphite was of 20 mesh, used: with this very iie iron the action wasconsiderably slower. This series of tests, show, therefore, a dissodiumvapor cannot so easilypenctrate the interior of the mass whereby toethnically contact with the reactive surfaces (or as I herein boardlyterm it, reactive surface).

On the other hand, when the graphite particles are too coarse the fineheavy particles or iron will tend to drop through the interstices andthus become segregated. The latter action would, in extreme cases,beequivalent to removing the catalyzer from the field of action. I findthat either of these two extremes may substantially result in thefailure to produce cyanid. f

It is to be understood that while Iregard finely divided iron. asgenerally preferable for use in the process, in view of the possibilityof increasing the potency of certain other factors hereinafter referredto, I do not wish to be limited to any particular .size, condition orsource of the catalyzer or indeed of the size, condition or sourceofcarhon for the same. For example, pulverulent iron may be produceddirectly in the react ing mass itself from iron compounds or ores, suchas oxids, carbonates, and the like, 6. (1., hematite, magnetite,siderite'and iron scale. A mixtu're'of finely powdered hematite, carbonand'sodium. carbonate may be pre pared in such proportions as to leavethe 1ron, graphite and sodium carbonate'ni favorable proportions forcyanid synthesis after the excess of graphite had reduced. the hematiteto metallic iron with the evolution of carbon monoxid. Under thesecircumstances the iron becomes reduced very readily (even if the solidcarbon particleslshoilld not come in thorough contactaviththeiron ore,reduction would still take place completely because the molten cyaniclformed reduces iron oxide with the utmost case and even carburizes theiron at the same time). Further, if the temperature be suificientlyhigh, sodium vapor will be formed, which, of course, will act as a.powerful reducing agent.

(arbour-The carbon may be supplied from a variety of suitable. sourcesand in addition to those mentioned, which are solids, carbon supplyingvaporsinay be used. Thus the hydro-carbons, e. g). petroleum, areavailable for use in certain cases. highly desirable usually tosubstantially completely exclude the oxygen of the atmosphere fromparticipation in the reaction resulting in the production of. cyanid,since oxygen either converts thccyanid formed to cyanate; or oxidizesthe iron and results in the production of ferro-cyanids or the-like uponsubsequent lixiviation; or even worse, it may destroy the cyamdfornicthwith reproduction of carbonate. The carbonhas greater freedom ofmotion than one ni ghtat first expect. Its diffusion is not limited tou'ierhanical motion due. to the actionof gravity, agitation of the mass,melting'of its It is solid material with consequent sintcring, .washineffect on the particles by currents of liquid us to surface tension,change of concentration, ca illai'ity, distillation of liquids etc. Itis solu 1c in the iron, or the like, use

. as a catalyzer, and can diifuse either in the form" of solid or liquidsolution. It may, in effect, be'ca'rried as liquid, vapor, or even assolid in the form of sublimate, by compounds such as cyanide, e. g.sodium cyanid. If these compounds come in contact with iron lacking incarbon, a reverse action may take place, thus helpin to carburize themass of iron. Indeed, t is imparts a mobility to the carbon such aswould be attained if'the carbon could difluse as a vapor, thus giving tothe carbon, such as graphite, coke, charcoal, etc., in the tube,essentially the same kind of freedom that it would have if used in theform of hydro-carbons.

, All-alt metaZ.'The source of alkali metal 'or other base of the.cyanogen compound formed during the course ofgthe process, is preferablysome. inexpensive compound such as sodium carbonate,'sodium bicarbonute,sodiumhydrate, or the like, but it is possibleto employ initiall freealkali metal or its equivalent, and int ose of the claims herein setforth which are of suflicient sec 0' to be readable upon'a process usinginitial fi' free alkali metal or its equivalent as We as upon alkalimetal other than initially free (in other words, where the alkali metal,or a volatile compound thereof, is supplied from a source of the same,'relatively remote from the-reaction zone) are not to be deemed as beinglimited to such supply of alkali metal, or the like, froman existingcompound ofxthe same,

With respect to sodiumbicarbonate I per.- ticularl desire to callattention 'to thejfact that I ave successfullyjused the moistbicarbonate which comes from ,the ammonia soda process;v and thiswithout previous drying: Indeed, very many impure alkali compounds whichmay result from various technical processes can be converted into purecyanogen compounds. For example, mixtures of alkali hydroxids,carbonates, acid carbonates, acetates, oxalates, etc., can be useddirectly if -ir on, oxids, or hydroxids or organic salts of iron,'carbon or organic mat-- ter in eneral be present; and no contamination ofthe alkali cyanide can occur since the substances of.-.the classesmentioned are so transformed in the process that the only 1 negativeradicle remaining will be cyanogen. If more than one alkali m hal bepresent,

however, a mixture of alkali .yanE .ls will result. When the cyanidobtained is to be transformed into ammonia as hereinafter 'describedalmost any other impurities may be present without affecting the purityof the product, providing suitable precautions are taken. It is obvloustoo thatsodium' car- 7 ferred to.

-ferred to, that. for the production of cyamds, the nitrogen is derivedfrom coal more or-less directly presenting the reactive solution exertan enormous influence when we consider its various effects. It increasesthe velocities of chemical reactions enormously,

and it also increases the rate at whichthof carbon goes into solution inthe iron; as well as the rates of gaseous dillusion and de. velopment ofvapors. The temperatures of the operation further intimately concernsthe surface and contactconditions above re- 1 further do not wish to berestricted to any particular lower temperature limit, and indeed Icontemplate effecting the process in certain cases at temperatures beloweven 700 (3., since rubidium and caesium carbonates, for example, andespecially mixtures of these'or of one or more of: these with sodium orpotassium carbonate or analogously acting compounds permit of materiallylowering the temperature at which the nitrogen fixing reaction takesplace (principally, I believe, by increasing the fluidcirculation) H Byincorporating cyanids initially in the reaction mixture, the same endmay. also be attained in a measure.

I desire in the present divisionof my said parent application to pointout more particularly the utilization of certain of the steps of myeneral process in forming ammonia or the like substantially by a directreaction.

-'Dr. Ewan states in his article in Thorps Dictionary of AppliedChemistry, above rein every process now used This is equivalent tosaying that the cyanids are, in general, prepared from ammonia. Incontrast to this, one of the main objects of the present invention isthe commercial production of ammonia through the instrumentality ofcyanide produced from atmospheric nitrogen; thus making the productionof ammonia independent of the use of initially combined nitrogen.Indeed, as intimated above, I contemplate effecting, in some cases, theproduction of ammonia in such a mannor that the cyanid formation will bebut momentary or evanescent, so that. in efiect.

the ammonia may be produced 'not'onl syn thetically but practicallydirectly. This last can probably best be referred to while con sideringthe phase of the process which involves the formation of cyanid as adefinite and intermediate step.

'A1mnom'a.-Assuming that the apparatus shown by way exemplification hasbeen charged with iron, carbon and a preferabl inexpensive alkalicompound, all in suitab e form or condition and properly disposed withrespect to each other to yield alkali through it. -.\mmonia will beproduced ac-- cording to the following equation.

\Ve show that '0 have here a cyclic process for producing: ammonia fromair and water through the instrumentality of car bon l alternatelypassing nitrogen or steam through a mixture consistimg of iron, carbonand, for example. sodium carlmnatc.

If desired, the carbon monoxid and hydrogen may be burned with air, thusproducing heat, which may be utilized in the process, and -a.mixture ofcarbon dioxid, hliilOflQfl and water. The water condenses and the carbondioxid and nitrogen together. with the ammonia already formed may bepassed into a solution of sodium chlorid, as in the ammonia-sodaprocess. The carbon dioxid of the mixture is thus ultimately utilized toform sodium bicarbonate, or sodium carbonate. leavingthe nitrogen in afairly pure form for use in the preparation of another portion of cyanidaccording, to equation l.

The process is admirably adapted for use with the ammonia-soda processas it may utilize the waste atmospheric nitrogen from this process tofurnish the pure ammonia, required in the latter process, very cheaply.The expense of the ammonia as well as the troubles arising from theimpurities liable to be contained in commercial ammonia are at presentseriou obstacles to the economical operation of the ammonia-sodaprocess; but both of these ditliculties are obviated it'. ,lny processis used in er'mnect-iou therewith.

The sodium carbonate acts cyclically to fix nitrogen by beingtransformed into cyanid and then the cyanid is changed back intocarbomite, (equation 3), by the use of steam. If desired, we may startwith the cyanid instead of the carbonatc,in thiscycle. For example, amixture of potassium cyanid, carbon and iron may be heated in a currentof steam until a substantially quantitative yield of ammonia 'sobtained. The steam is then displaced by a current of nitrogen and thetemperature is raised to about 1100 C. In a short time the action willbe completed and the retort will be found to contain much cyanid; thepotassium carbonate ha ring again been transformed into cyanid.

Upon adding carbon as required, the proc- T' ess may be repeated overand over again as the cyanid or carbonate acts cyclically while the ironacts catalytically. The temperature should not be too high, otherwisetoo much oxidation results from the steam and there is more tendency forcyanogen compounds to pass over with the ammonia.

\Vhen the temperature is at lequate but not excessive. very little ofthe cyanruzen compoumls will pass over with the ammonia, and even thesecan be recovered very easily by using suitable scrubbers. If desired,thc ammonia may be obtained from the scrubbers in anhydrous form.

My present invention contemplates the production of ammonia in suchmanner that the cyanid formation will be transitory or evanescent. To soetl'ectuate the process it is merely necessary to reduce the temperagture of the operation to a point (approximately 725 C.) where while thecyanid forming reaction is proceeding, the reaction shown in equation 3may also occur. Under such conditions the catalytic material, iron,previously considered. is supplemented by the alkali metal carbonatewhich now may be regarded as an auxiliary catalyzer. The equation. maybe represented thus: i

(l) Nfi-lC-i-HLO-lsodium carbonate+i ron In this case one of thecat-alyzers (e. iron) pnobably acts passively or merely as a solvent forone of the actively pai'ticipat-' ing, elements; while the second orauxiliary catalyzer is itself actively involved in the reaction. Thecyanid is prolmbly intermediately produced, and in effect simultaneously\vith the'ammonia. If desired, however. the production of ammonia may beeffected at the same or a slightly higher temperature. let us say forexample, 750 C., by passing the nitrogen current until a proper cyanidformation has been effected, then substituting steam for the nitrogencurrent. thereafter alternating the nitrogen and steam, thus also ineffect using the alkali carbonate as a catalyz'er, the temperature beingmaintained substantially constant. it desired.

General rewmrks.-()\ving to the numerous possibilities of the process.have only described some of the more important steps involved, hence Iwish to be limited only by the general spirit of the above disclosuresand by the appended claims.

For convenience, I have described most of the operations, and writtenthe corresponding equations, for sodium compounds; but thesedescriptions are intended to apply to alkalicompounds generally. and.where applicable, to metals capable of performing like functions in theprocess.

Having thus described my invention what I claim is: Y

1. The process of fixing nitrogen which comprises brin 'ng initiallyfree nitrogen into contact wit carbon dissolved in a mass I ofcatalyticmaterial presenting an extended mately 725 -C.,

carbon with-said nitrogen-as cyanogen and so i 2. The process of fixingnitrogen which comprises bringing initially free nitrogen into contactwith carbon dissolved in a mass- =0f catalytic material presenting anextended solution surface, and heated to approxicombining the dissolvedreacting upon the latter substantially directl as formed with a,substance capable of yielding the element hydrogen, whereby to combinesaid nitrogen w th; said hydrogen. i

3. The process of fixin nitrogen which comprises bringing initia ly freenitrogen into contact with carbon dissolved in a mass of catalyticmaterial. presenting an extended solution surface, combining thedissolved.

carbon with said nitrogen as cyanogen and reacting upon the lattersubstantially directl as formed with a substance capable of yiel, ingthe element hydrogen, whereby to combine said nitrogen with saidhydrogen. 4. The process of fixing nitrogen which comprises causingsuccessive reactions in the immediate vicinity ofa mass of metalcontaining dissolved carbon, to, first evanescently combine said,dissolved carbon with free nitrogen and to then immediately recombinesaid nitrogen with hydrogen, by

contacting free nitrogen molecules with carbondissolved in said metal,and simultanei ouslyicontacting said molecules with those of a compoundthe base of which is adapted to act asthe base of a cyanogen compoundand immediately reacting upon the resultant product with a substancecapable of yield- 1 mg hydrogen, said first mentioned compound aud saidmetal acting catalyticall 5. The process of fixing nitrogen w ichcomprises causing successive reactions in the immediate vicinity of amass'of metal containing dissolved carbon, to combine said dissolvedcarbon with free nitrogen and to gen, by contactin free nitrogenmolecules with carbon-disso ved in said metal and si- '60 then recombinesaid nitrogen with hydro-' multaneously contacting said molecules withthose 'of a compound the base of which is adapted to act asythe base ofa cyanogen compound, and reacting upon the resultant product with asubstance capable of yieiging hydrogen, said first mentioned co poundand said metal acting catalytically.

6. The process of fixing nitro enwhich comprises preparing a mixture 0 apluralof analogous compounds the base of each it of which is adapted toact as the base of a cyanogen compound, said mixture having a.

melting point materially below that of any.

of its constituent compounds, subjecting said mixture to heat, to meltthe same, and to the action of carbon, dissolved in material,

capable of rendering said carbon reactive, and further to contact withfree nitrogen and a substance capable-of supplying hydrogen to theresultant compounds formed by reactions which may be effected betweensaid reactive carbon, n trogen andisaid first .nientioned com ounds, andthereby effect ing two sets 0 reactions in se uence, the first of which.yields said resu tant compounds'and the second of which unites thenitrogen thereof with hydrogen. I

In testimony whereof I have aifixed my signature, in the presence of twowitnesses. JOHN E, BUCHER. Witnesses: NORMAN E. Hour,

THOMAS H. ROBERTS.

